This sounds like the correct answer. A signal booster. I have friends who needed to put one in their steel sided and roofed shed.
Buster 50 - 6/22/2020 15:18
More background would help. An I-6 is an older phone so did this just begin? Did you recently put metal shingles on the house? Are the barns steel on both interior and exterior walls? My I-6 would lose signal in my shop until I put a signal booster on it. | 
I phone 6
